Scuba divers from Northwest Underwater Contractors did an underwater survey of the Leaburg Dam’s fish ladder last April that revealed erosion has undermined the structure’s concrete foundation.

LEABURG: Scuba divers inspecting Leaburg Dam’s left bank fish ladder had bad news after an underwater inspection of the structure last summer. They reported that some seventy feet of the concrete foundation had been undermined.

The fish ladder, constructed in the 1960’s, was poured directly on the river bottom, which is comprised of cobbles, sand, and gravel. Riprap was placed adjacent to the fish ladder in an effort to prevent erosion. Divers found the undermining ranged from four feet to more than fifteen horizontal feet, measured from the riverside foundation to the face of the fish ladder.